﻿//#define _CRT_SECURE_NO_WARNINGS 1
//
//#include<iostream>
//#include<cmath>
//#include<iomanip>
//
//using namespace std;
//
//
////double area1(double x, double y);//求长方形面积
////double area2(double, double, double, double);//求三角形面积
////double area3(double);//求圆面积
////double area4(int&);//求正方形面积
//
//
//double area1(double *a, double *b)
//{
//	//double s = a * b;
//	return s;
//}
//double area2(double c, double d, double e)
//{
//	double p = 0.0;
//	p = (c + d + e) / 2.0;
//	double s = sqrt(p * (p - c) * (p - d) * (p - e));
//	return s;
//}
//double area3(double f)
//{
//	double s = 3.14 * f * f;
//	return s;
//}
//double area4(double g)
//{
//	double s = g * g;
//	return s;
//}
//int main()
//{
//	double a = 0.0, b = 0.0, c = 0.0, d = 0.0, e = 0.0, f = 0.0, g = 0.0;
//	cout << "rectangle:" << area1(a, b) << endl;
//	cout << "triangle:" << area2(c, d, e) << endl;
//	cout << "circle:" << area3(f) << endl;
//	cout << "square:" << area4(g) << endl;
//	return 0;
//}